#!/usr/bin/python3
# -*- coding: utf-8 -*-
"""Plot horizontally-stacked bars with Unicode and ANSI escapes.

Example usage:

    ./barstack.py 38 7 22.1

This will plot three bars with proportional sizes 38, 7, and 22.1, one
next to the other, which together fill the horizontal width of the
screen.

For a good time, call

    x=950; y=0; for i in {1..512}; do
        ./barstack.py "$((1000+$x))" "$((1000-$x))" "$((1000+$y))" "$((1000-$y))"
        : $((y-=((x+=($y>>5))>>5)))
    done

I’m thinking maybe to add palettes, 24-bit colors, textual legends,
appealing contrasting text colors, and so on.  In old versions of
gnome-terminal and Konsole, the characters in question don’t display
correctly (there’s some space left above them in the character set,
resulting in incorrect pixels).  In Termux there is a spurious space
both above and below the block character.  xterm and recent versions
of gnome-terminal and Konsole seem to work reasonably well.

"""
from __future__ import division, print_function
import argparse, os


# Left eighth blocks, in reverse order, followed by a space.  U+2590
# and up, except for the space.
blocks = '▉▊▋▌▍▎▏ '


def parser():
    formatter = argparse.RawDescriptionHelpFormatter
    p = argparse.ArgumentParser(description=__doc__, formatter_class=formatter)
    p.add_argument('-n', '--no-legend', action='store_true',
                   help='Omit textual legends within bars')
    p.add_argument('-w', '--width', type=int, default=guess_terminal_width(),
                   help='The terminal width to target (default %(default)s'
                   + ' on this tty)')
    p.add_argument('q', nargs='+',
                   help='The numbers to plot')
    return p

def guess_terminal_width():
    termsize = os.popen('stty size').read().split()
    if not termsize or int(termsize[1]) == 0:
        return 80
    else:
        return int(termsize[1])

class InvocationError(Exception): pass

def plot_absolute(positions, legends):
    pos = 0
    output = []
    for color, (desired, legend) in enumerate(zip(positions, legends)):
        assert desired >= 0, desired
        assert desired >= pos, (desired, pos)

        output.append('\033[3%d;4%dm' % ((color - 1) % 8, color % 8))
        if pos % 8:                        # advance to character cell boundary
            jank = 8 - pos % 8
            output.append(blocks[jank])
            pos += jank

        w = max((desired - pos) // 8, 0)
        label = str(legend)
        output.append(label.center(w) if len(label) <= w else ' ' * w)
        pos = desired

    output.append('\033[0m')    # reset

    return ''.join(output)

def plot(args):
    ss = [0]                    # sums
    for qi in args.q:
        try:
            qi = int(qi)
        except ValueError:
            qi = float(qi)

        if qi < 0:
            raise InvocationError("bar size must be nonnegative", qi)

        ss.append(ss[-1] + qi)

    width = 8 * args.width
    return plot_absolute([int(round(qsi * width / ss[-1])) for qsi in ss[1:]],
                         [''] * len(args.q) if args.no_legend else args.q)

def main():
    print(plot(parser().parse_args()))

if __name__ == '__main__':
    main()